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Center post size matter


Angel Goday
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Hi all, I have some doubts of which center post diameter to choose.


As far as I know there are the following post:
2"  ( Mk-v , XCS)
1,89" ( Betz tools, Artemis)
1,75" ( tiffen  M1, among others)
1, 58" (tiffen M2, among others)
1,5 ( Gpi pro, among others)

As some of the brands due it´s modularity have the posibility  to choose which diameter post it fits you. I would like to know  the important things to you to have in mind before to choose one or another.

I know that some of you prefer thicker center post because it give you "more control" in your hands, others operators do not.

I know the Volt system it fits in center post up to 1,75". But Betz tools has adapted in their sled RIG of 1,89" so that matters to choose one or another.

I know that the thicker center post are less flexible so less vibration on bigger cámera packagges. But how big has to be a camera packagge to be a point breaker to choose a 1,75" over a 1,58" post, or another?

Any has found that his/her sled diameter center post has been an issue? Did you have that day that you say: Damm I should  had choosen a thicker sled...or Damm I should have choosen a thinner one.. and Why?


Thanks in advance for your time and help.
Angel Goday.

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In general, a larger centerpost diameter equates to a stiffer post, but that is not the only factor that determines stiffness. The inner diameter of that post, or wall thickness, also plays a part, as does the material – like different aluminum alloys. With carbon fiber centerposts, many other factors, including the weave, also come into play, creating more stiffness in some directions than others. And stiffness of the centerpost is only one of several factors in reducing or eliminating vibration in a sled. The weight of the camera & accessories play a huge role. What are you going to be carrying? Are you running? Doing slower moves in a studio?

 

The “feel” of a larger centerpost is actually about the “feel” of the gimbal – its diameter and its knurling or operator added tape. With many gimbals, the gimbal’s diameter is much larger than the centerpost’s (like the PRO) or the same diameter, regardless of the centerpost diameter (M1/M2 for instance).  Larger gimbal diameters give you more oomph (I’m being highly technical here, I know) on the sled, but it’s clearly too much for sleds with little inertia – hence the smaller control surfaces on the “little” Steadicams – like the Flyers and Aeros and the old JR.

 

Centerpost diameter affects what is attached to it. Monitor rods of the standard 15mm on 60mm centers cannot clear a 2 inch centerpost. Although those rods could clear a 1.75 inch centerpost by .017 inches on each side, the strength of the mount would be compromised. The Tiffen monitor rods for the 1.75 inch centerpost are 15mm diameter on 100mm centers. While perhaps stiffer, there are three negative consequences of having wider monitor rods. One is that standard 15mm x 60mm c to c accessories – such as used on the rods from many stages for low mode monitors and MDR’s, can’t be used on the monitor rods. 2nd is that the monitor rods are wider right where your thighs are, so the sled must always be a tiny bit further away from you. And 3rd, bigger diameter centerposts and their gimbals, mounts and clamps weigh more than thinner ones. Maybe it’s not a big deal unless you are doing live TV, sports, or concert work where you are wearing the rig for a long time.

 

So, IMHO, the question really should not be about centerpost size per se, but what system has the gimbal that feels right to you and a centerpost  which has adequate stiffness for the jobs you do, and a system that doesn’t weigh more or take up more space than necessary.

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Thanks Jerry for taking the time to answer. Very informative. I,ve learnt a lot. I really appreciated.

The operators I know here they use mainly MK-V, Betz tool and Artemis. But they already started with that thicker sleds so they don´t know about thinner ones.

 I'm working in a standard Advertising, Tv series environment, nothing too low budget, nothing too big.

With regular package of Alexa LF or Sony Venice with  Cooke S4 , S7, Arri master primes, etc..To time to time It will apear some Hawk anamorphic lenses. Or we use some of the new angenieux short zooms 28/76

That will be camera package between 9kg to 16kg   (20 pounds/ 35 pounds.)

My concern it,s if the carbon fiber centerposts of 1´58" ,it will be stiff enought to get the  job done with out vibration or I will have to consider a bigger center post,  starting in a 1,75" size up to a biggers one.

Or maybe I shouldn't be too concerned about sizes and pick up the one feels "right" to my hands and my budget. I´m trying to avoid to buy a new sled and then be regretted in a shooting day.

Thank you so much.

 

Edited by Angel Goday
misspelling a word
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Angel-

1.58 is the diameter of many (CP and Tiffen) carbon fiber center/gimbal posts that I've been using for 30+ years... plenty strong and stiff enough for most work. Really long (superpost) center posts are probably somewhat better with a larger diameter center post, especially if the moves are violent. My 4 section Ultra 2 has a 1.58 centerpost for the gimbal, and two larger diameter posts going towards the battery and one inner, smaller diameter post going towards the camera. When compact, it's bulletproof. If fully extended to 6 feet – and the shot is pretty aggressive or rough – it helps to use tensioning cables to reduce the flex (it's part of the U2 design & the patent). The M2's 1.58 center post is plenty strong (I have a lot of experience with it). The 1.75 is stronger, of course, and comes with a 3 section option.

I often worry that new operators (and some older ones) focus on one aspect, number, technique, etc., and don't consider it in light of many, many other important considerations of buying and using the gear. Especially in forums like this one, where an operator necessarily asks a question in isolation, simple answers often inflate both the importance of the question and any answer. It's why an intensive workshop is so important, where a broad spectrum of technical knowledge and operating wisdom is presented, and questions like center post size (an important question on its own) can be addressed and not blown out of proportion.

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Thanks Jerry! You just gave me all the information I needed and solved all my doubts.

I´m completly agree about the Workshop, I jus did the Golden workshop last year in Tenerife (which I highly recomend) with Chris Fawcett amongs another fantastic Steadicam operators with tones of experience.

As I´m looking for a new Sled, I realized that I still had to solve some doubts.

Thanks again Jerry!!

Best of Luck,
Angel Goday.

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